<p>Poly(3,4-ethylenedioxythiophene)–polyindole (PEDOT–PIn) is a distinguished π-conjugated conducting polymer; however, its inherent brittleness and loosely arranged molecular framework hinder its long-term operational reliability in practical devices. To address these shortcomings, a novel niobium nitride (NbN)–PEDOT–PIn hybrid nanocomposite is synthesized, featuring a mechanically stable three-dimensional network formed by embedding PEDOT–PIn nanostructures within stratified layers of NbN through a controlled oxidative polymerization strategy. This multifunctional material functions both as a high-efficiency electrode for electrochemical energy storage and as an effective catalyst for electrochemical and photocatalytic applications. The hybrid material exhibits outstanding electro catalytic sensitivity toward Fenbendazole (FNB), as assessed by differential pulse voltammetry (DPV). As an energy storage medium, the NbN–PEDOT–PIn composite enables rapid and reversible ion storage processes, as demonstrated by galvanostatic charge–discharge (GCD) testing, where the hybrid electrode delivers a high specific capacitance(SC) of 680 F g⁻¹ at a current density of 1 A g⁻¹. Cyclic voltammetry (CV) and log–log plot analysis confirms a capacitive contribution exceeding 97%, indicative of dominant surface-controlled charge storage behavior. The electrode also demonstrates exceptional electrochemical durability, maintaining nearly 100% coulombic efficiency over 2000 continuous cycles, highlighting its superior long-term stability and robustness. In addition to its electrochemical sensing and energy storage capabilities, the composite exhibits excellent photocatalytic performance toward dye degradation under visible-light irradiation, achieving 99.72% methylene blue (MB) removal efficiency with a kinetic rate constant of 9.17 × 10⁻⁶ mM s⁻¹ under optimized conditions. The strong electronic coupling between the NbN matrix and the PEDOT–PIn polymer enhances electron transfer dynamics, boosts redox reactivity, and stabilizes the composite structure factors that collectively contribute to its superior performance. Under UV–visible illumination for 90&#xa0;min, optimal photocatalytic degradation of MB is achieved at 5&#xa0;mg/L MB, establishing favorable conditions for combined adsorption–photocatalytic processes. These findings validate the NbN–PEDOT–PIn composite as a dual-purpose nanomaterial with promising potential for next-generation energy storage platforms and advanced wastewater treatment systems targeting organic dye contaminants.</p>